Apparatus for the manufacture of tin plate



Dec. 30, v1941.

` H. sEBELL APPARATUS FOR THE MANUFACTURE OF TIN PLATE Filed July 13, 1940 3 Sheets-Sheetll www Dec. 30, 19,41. H. sEBELl.. 2,267,877

APPARATUS FOR THE MANUFACTURE OF TIN PvLATE Filed July 1s, 1940 A s sheets-sheet 2 v lnvenor. Hurry Seben by7aud Ays.

Dec. 30, 1941. H. sEBELl. 2,267,877

APPARATUS FOR THE MANUFACTURE oF TIN PLATE l File-d July 15, 1940 3 swag-sheet 3 Ylnvemcm Sebell ATIyS.

v f #n O |Il lll Ill lll

H c1 mjy byjawml/f Patented Dec. 30, 1941 5 APPARATUS FOR THE MANUFACTURE 0F v' TIN PLATE Appiicauon July 13,

Harry Sebell, Newton, Mass., assignor of one-half to Arthur H. Parker,

Lexington, Mass.

1940, Serial N0. 345,322 y s Claims. clL en -12.7)

This invention relates to coating sheet iron and particularly to providing sheet iron with a coating of metal such as tin or zinc.

In order to simplify the description of the` invention, I will refer to it hereinafter as used in the manufacture of so-called tin plate, that is, sheet iron which is provided with a thin coating of tin. y

According to the present practice, tin plate is made by passing sheet iron either in the form of separate plates or in the form of a long strip,

through a bath of molten tin containedin a socalled tin pot, said pot having at the entering side, that is, the side at which the sheet metal is entered into the pot, a ux box containing flux through which the sheet metal passes before it enters the bath of molten tin, and also having on the discharge side a compartment containing oil through which the coated sheet passes as it emerges from the bath of molten tin. y

The sheet metal entering the bath' of molten tin has a chilling eiect on the tin, this being partly due to the heat absorbed from the molten tin to heat the sheet metal, and partly due to the heat absorbed from the molten tin in evaporating the moisture which remains on the surface of the sheet metal after its passage through the pickling bath.

. This. chilling effect on the molten tin controls to a certainextent the speed 4at which the sheet metal can be fed into and passed through the tin-bath, for if the sheet metal is moved into and through the bath at toorapid a rate, the chilling effect will'be such as tointerfere very materially with the coating operation.

One of the objects o`f my present invention is to provide an improved apparatus which is constructed so as to reduce to a minimum the chill? ing effect on the molten tin caused by the sheet metal entering the tin bath, thereby enabling the tinning operation to be speeded up to a point considerably in excess of that at which tin plate' can be produced with the machines now in comy mon use. y

A further object of the invention is to provide a novel coating apparatus so constructed thatthe mass of molten tin in the tin pot is maintained at its proper temperature not only by heat applied to the pot externally'in usual manner but also by heated means submerged in the mate' rial in the pot and so located as to provide substantially equal heat fiow therefrom in all directions. l

A still further object of the invention is to provide a novel apparatus by which the sheet 55 metal to be tinned is fed through the tin bath by means of heated rollers.A Such rollers not only assist in producing'a more even tin coating, but they furnish means for heating the tin bath internally, thereby offsetting to a considerable extent the chilling effect which the sheet metal has on the bath as it is fed thereinto.

In the drawings, wherein I have illustrated some selected embodiments of the invention:

Fig. 1 is a fragmentary sectional view illustrating the coating element. of a machine embodying my invention and adapted to coat sep-"- arate sheets.

Fig. 2 is a similar view of the machine adapted A to coat sheet metal in the form of a longstrip.

Fig. 3 is a section on the line 3 3, Fig. 1.

Fig. 4 is a fragmentary sectional view illustratin'g the means by which the separate sheets are cooled after they emerge from the tin bath.

Fig. 5 is an enlarged section on the line 55, Fig. 4.

Fig. 6 is a section on the line 6 6, Fig. 3.

Fig. 7 is a fragmentary view of the carrier for receiving the sheets after they emerge from the tin bath and while they are being cooled.

Fig. 8 is a sectional view showing a complete machine embodying my invention showing the pickling bath and the`coating apparatus. J

Referring first to Fig. 1, `I- indicates a tin pot of any suitable or usual construction containing a bath 2 of molten tin. This tin pot is shown as mounted in a suitable furnace 3 which is provided with a gas or oilburner 4 by which the pot is heated externally, said furnace having an opening 24 for discharging the products of combustion. In practice, this opening 24 would lead to ,a suitable flue pipe.

'/The tin pot I is constructed with the partiion 5 which extends downwardly tov a point i4/somewhat below the level of the molten tin. The llespace 6a on one side ofthe partition, the side which constitutes the entering side of the pot, l that is, the side` at which the sheet metal is fed into the pot, constitutes a iiux box containing a body of ux 6 which is supported on the molten tin 2, and the space 1'a on the other side of the partition, that is, the vdischarge side of the pot, constitutes an oil boxor grease box containing a body of oil 1 which also' is supported on the molten tin 2, this being the usual practice in devices for tinning. sheet metal.

In Fig. 1, 8 indicates separate sheets or plates of metal which are being fed through the pot to be tinned. Each sheet-enters the pot on the entering side and passes through the iiux 6 beer 4, yet the burner fore it is fed into the bath of molten tin, and each sheet is discharged from the bath of molten tin through the oil bath 1. p

In the operation of coating sheet metal with tin'as now commercially carried out, the plates to be tinned are rst submerged in a pickling bath and hence are usually wet when they are fed into and through the fiux 6. As the cool wet plates enter the molten tin, the latter becomes chilled somewhat, such chilling of the tin being partly due to the heat absorbed from the tin in heating the plates, and partly due to the heat absorbed from the tin in vaporizing any moisture on the plates. Although the molten tin is being continually heated by the burnis usually located below the tin pot and the chilling of the molten tin at the point where the plates enter the tin bath at the top is frequently so great that some of the tin becomes solidified or partially solidified, with the result that particles of the solidified or partially solidied tin adhere to the sheets as they enter the bath, thereby producing an imperfect coating. This chilling of the molten tin has a direct influence on the speed at which the sheet metal is fed to and passed through the bath of molten tin. The greater the speed. the greater the chilling effect, and Hence the practice is to advance the sheet metal at a slow enough speed to avoid any undue chilling of the molten tin.

In order to reduce the chilling effect on the molten tin, I have provided an apparatus in which the feeding means used for feeding the plates through the tin bath is heated and is constructed to heat ter and during their passage through the tin bath. In this way, the formation of solidified tin at the point where the plates enter .thermalten tin is greatly reduced, and, moreover, since the plates are heated by the feeding means while they are passing through the tin bath, any tin which is partially solidified and which adheres to the plate before the plate leaves the bath so that the plates which are discharged from the bath will be free from any particles of solid tin.

" In Fig. 1, 9 represents a pair of feed rolls which are partially submerged in the tin bath 2 of molten tin and partially in theilux '6, said feed rolls serving to feed the plates 8` downwardly through the ux and into the lmolten tin.

Situated within the bath of molten tin is a large `feed roller I which serves to feed the plates through the bath, said feed roller having smaller idler rolls II cooperating therewith. The

feed roller I 0 rolls II are presser rolls.

As each plate 8 is delivered from 'the feed rolls 9, it passes between stationaryguide plates I2 which direct it between the large feed roller IIJ and the first idler roll I I. 'I'he idler rolls'I I, be ing spring pressed, press the plate 8 against the feed roll, and said plate 8 is thus positively carried through the bath 2 of molten tin by the feeding action of the large feed roller I0.

As each plate 8 leaves the large feed roller I0, it passes between guide walls I3 and then between two pairs of'driven rolls I4, I5 which serve -to deliver the plate from the oil bath.

Each idler roll II is shown as carried in bearings 25 that are mounted between guiding ribs 26 formed on theend walls of the pot I. Each is positively driven and the idler spring pressed .and thus act as the plates before they en-A will become melted again bearing,25 is acted on-by a spring 21 which yieldingly forcesit ytoward the large feed roller I0 Suitable means are provided for heating the large roller I0 to a high temperature so that each plate 8 is being fed through -the tin bath by heated feeding means. The feed roller I8 is shown as in the form of a. hollow drum, and in Figs. 1 and 3, there isprovided a gas burner 23 provided with burner openings 24 which extends into the drum and serves to heat the latter. The drum or large roll I 0 is provided with trunnions I8, I9, which are journaled in bearing members 20. 'Ihe trunnion I9 has rigid with it a sleeve 2'I which extends through the Wall of the furnace 3 and carries at its outer 'end a gear 22 by which the drum I0 is rotated.

Said gear may be connected to yany source of power. The trunnion I8 is shown as hollow, and the wall of the tin pot I has an opening therethrough in alinement with the opening through the trunnion I8, thereby providing an exit for the products of combustion.

Instead of using a gas or oil burner for heating the drum I0, I may use an electrical heating unit withoutin any way departing from the invention.

vThe feed rolls 9, as well as the idler rolls II may be heated rolls, and hence, as each plate 8 is fed into the machine, it becomes heated by its contact with the feed rolls 9, and it continues to receive heat while passing between the drum I0 and the idler rolls I I.

The feed rolls 9 and the idler rolls I I may be heated in any appropriate way Without departing from the invention.

Merely for illustrative purposes, I have shown each roll as in the form of a tube and have also shown an electric heating unit 28 which is illustrated diagrammatically in Fig. 3, for heating each of the rolls 9 and II.

I1 indicates wipers cr brushes which contact with the feed rolls 9 and serve to keep the rolls clean and free from any tin oxide or solid tin particles which may be formedat the point where the plates are fed into the machine, or

' any iron particles which may be carried into the'bath by the plates.

The feed rolls I4 are also shown as provided with Wipers or brushes 30 for the purpose of keeping the surface of said rolls free from any solid particles which might injure-the tin plating.

By employing heated feedrolls 9 for feeding the plates 8 into the bath of molten tin, and by employing heated feeding meansfor feeding the plates through said bath, only a portion of the heat required to heat the plates to the proper temperature is taken from the molten tin. the rest of the heat required for this purpoes being received from the heated rolls. Thus the chilling effect of the plates 8 on the bath ofvmoltenmetal will be greatly reduced, thereby obviating to a large extent the formation of solid tin particles. Since the heated feed roll or feed drum I 0 is submerged in the material in the pot I and is internally heated, there will be a substantially even heat flow from said feed drum in all directions. In other words, there will be a heat ow from the lower portion of said drum to the plates passing'v around the drum and heat flow from the possible to feed the plates for subjecting ber 'of direction heated, there will be a substantially equal heat flow from each of said rolls in all directions,

.This heat flow from the submerged drum I into the portion of the molten tin through which the plates enter the'tin bath serves to replace the heat loss suffered by said molten tin dueto the feeding of the cold sheet metal into the bath. The drum l0 and the rolls 9 are, therefore, important factors in maintaining the molten tin at its proper temperature, which is in the neighborhood of approximately 575 F., at the points where the plate or strip enter and leave the bath.

These factors all cooperate to `speed up the tinning operation so that with my invention it is 8 through the tin bath at a speed which is considerably in excess of that at which such plates are usually fed through the tin bath, without producing any deleterious chilling effect on the molten tin.

I will preferably employ a, feed roller Il) of sufficient diameter so that its peripheral area is two or three times more than the superficial area of any plate so that when said plates are being fed throughy the bath of molten tin, each plate Will have its entire surface in engagement with the feed roller or drum Il! for a definite time period. In this way, all portions of any sheet are simultaneously subjected to the heating effect of the drumv I0 during such'time period.

In Fig. 2, there is shown an apparatus similar to the one illustrated in Fig. 1, but adapted stead of separate plates 8. In this embodiment, the strip 8a is fed into the machine by the feed rolls 9 and is fed through the bath 2in the same manner vas above described. Fig, 2 illustrates also the feed drum I0 as being heated by an electric heating unit indicated conventionally at 3|.

As stated above, it is customary to submerge the sheet metal to be coated in a pickling bath just prior to delivering the sheet metal linto the coating bath, and in order to obtain the desired benefit from the pickling bath, it is necessary that the sheet metal should remain in the bath for a period of ten seconds or more.

As further stated above, it is possible with my apparatus to advance a strip of sheet metal 8a through the coating bath at a speed considerably in .excess of that possiblewith machines now in use without producing any deleterious chilling effect on the molten tin, and in order to provide the sheet metal to the pickling rolls 51, 58, 53 may be employed in order to maintain the strip inthe pickling bath for the reouired length of time. y In the operation of applying a tin coating to plates 8, it is'necessary .to allow the plates to cool somewhat after emerging coated faces out of contact with any object and in the form of an endless f members 33,

for a sufhcient length of time to permit the tin coating to harden by cooling. Such device is carrier constructed to engage and retain the plates by the edges This carrier comprises two endless bands or each having apertures 34 to receive the teeth 31 of sprocket wheels 36, 38, 39 and 40, around which the endless bands 33 pass.

Each band 33 is provided with outwardly prol jecting inclined arms 35. The sprocket wheels 3B, which are mounted on a shaft 42, are situat'ed adjacent the delivery side of the tin pot and in such a position that as the separate plates to operate on a long strip of sheet metal 8a in- 8 are discharged from the squeeze rolls l5, the leading end of each plate will be carried into a position between the outwardly extending arms 35 of the two endless bands 33, so that the side edges only of the plate Will be engaged by these arms, as shown in Fig. 5. It will be noted that each plate 8 is delivered from the squeeze rolls I5 at a slight'angle so that as the leadingend of the plate moves upwardly into the dotted line position, Fig. 4, said leading Aend will -tend to gravitate toward urally into the space between the arms 35. The frictional engagement between the arms 35 and the edges of each coated plate 8Awill be sulilcient to carry saidy plate along with the carrier, and as the carrier is fed around the sprocket wheels 38, 39, the coated plate Will be carried thereby.

It will be noted that'each plate is curved in the direction of its length as it is passing around the various sprocket wheels, and such curvature prevents the plate from tudinally by any pressure the plate andthe arms 35. By the time each being buckled longiplate reaches the vertical lefthand run of the bath for the requisite period of time, notwith- 4standing the relatively' rapid advancing movement of said sheet through the bath of molten tin, I propose to use a pickling bath such asV shown in Fig. 8. In said gure, indicates a tank containing a pickling bath 56, which is usually an acid bath. are driven' rollers Located within the bath 56 51, 58 and 59, around which the strip 8a of 'sheet metal passes, said stripbe- Y ing takenfrom a coil 80. The sheet metal passesl from the coil 60 over a roller 6I, and thence into i the pickling bath and around thedriven rolls 51, 58 and 53. The strip then passes between squeeze rolls 62 which feed the strip forward, and

over. a direction roll 53, to the feed rolls 9. By

. Yis situated to endless carrier, it has become cooled sufficiently so that the tin plating will not be marred by contact with any object. Each plate is discharged from the carrier by means'of a finger 4l which engage each plate as it reaches the lower end of the vertical run. As each plate is discharged from the carrier, it is received by a platform 5l, a travelling belt or any other receiving element. 1

It will be understood that the power for driving`the endless bands 33 can be applied thereto through any one of the shafts 42, 43, 44 or 45,

25 indicates guiding bars or blades that are located between the various presser` rolls. Such guiding elements serve to guide the leading edge of each plate from one presser roll to the bite between the next presser roll and the feed roll I0.

It will thus be' seen that I have provided an apparatus for coating sheet metal in which the sheetv metal to be coated Y is f ed through the molten coating material by heated feeding means, which serve to heat the sheet metal, with the result that the amount ofheat. which the sheet from the oil bath and before they are polished. This cooling pethe left and willthus fall natbetween the edges of metal absorbs from is considerably reduced.

It will also be noted that in my improved apparatus, the heat for maintaining the coating material at the proper temperature is obtained .partially from the burner 4 which applies heat externally to the pot and partially from heating means (herein shown as feed rollers) located within the pot.

With my apparatus, therefore, the molten metal is maintained at the correct temperature by heat applied both externally and internally thereto.

I claim: y

1. An apparatus for tin comprising a pot containing molten tin,

means to heat the pot externally, a relatively large hollow feed roll entirely submerged in the mass of molten tin, means to rotate the feed roll to feed the sheet metal to be tinned through said molten tin, and means to heat the feed roll interiorly, whereby the heated feed roll serves to supply heat directly to the portions of the mass of molten tin at the points where the sheet metal enters and leaves said mass.

3. An apparatus for plating sheet -metal with tin comprising a pot containing molten tin, means for heating the pot externally, and heated feeding means .entirelyy submerged in the mass of molten tin for feeding the sheet metal through said mass and so located in said pot asl to have substantially equal heat flow in all directions whereby the heat loss due to` the Ifeed of the cold strip is replaced by the heat from the heating means. y

4. An apparatus for plating sheet metal with tin comprising a pot containing molten tin, flux, and oil, a relatively large rotary roll submerged 2,267,877 the molten coating material` in the mass of molten material in the pot and around which the sheet metal passes and with which said sheet metal has contact throughout a substantial portion of its peripheral surface, means to rotate said roll, means to heat said roll and therebysupply heat directly to the portion of the mass of molten material at the points where the sheet metal enters and leaves said mass, and a pair of feed rolls to deliver the plated sheet metal from said mass of molten material.

5. An apparatus for plating sheet metal with tin comprising a pot containing molten tin and provided with a flux box at its entering side above the mass of molten tin 'and an oil box at its discharge side also above said mass of molten tin, means to heat the `pot externally, a relatively large hollow feed roll submerged in the mass of molten tin and situated below the iiux in the flux box and the oil in the oil box, means to rotate the feed roll, thereby to feed the sheet metal to be tinned downwardly through the ilux box and around the feed roll and then upwardly through the oil box, and means to heat the feed roll internally whereby the heated feed roll supplies additional heat to the molten tin at the points Where the sheet metal enters and leaves the latter.

6. An apparatus for plating sheet metal with tin comprising a pot containing molten tin and provided with a flux box at its entering side above the mass of molten tin and an oil box at 'its discharge side also above said mass of molten tin. means to heat.the pot externally, a relatively large hollow feed roll situated within the pot and entirely submerged in the mass of molten tin, said pot having bearings in which the feed roll rotates and said roll having trunnions rotatable in the bearings, one of said trunnions being the wall of the pot, a driving gear onA said trunnion outside of said pot by which the roll is rotated to`feed sheet metal downwardly through the iiux box, around the feed roll and upwardly box, and a burner pipe extending feed roll and HARRY ysizBELL.

hollow and extending through,

hollow trunnion into the hollowv 

